Diamond plug or blast hole bit



June 26, 1951 E, C; BQNSALL 2,558,415

DIAMOND PLUG OR BLAST HOLE BIT Filed May 18, 1949 INVENTOQ A TmQA/EY Patented June 26, 1951 UNITED STATES PATENT ()FFICE DIAMOND PLUG OR BLAST HOLE BIT Edgar C. Bonsall, Falconbridge, Ontario, Canada, assignor, by mesne assignments, to J. K. Smit & Sons, Inc., Murray Hill, N. J., acorporation of New Jersey Application May 18, 1949, Serial No. 93,975

a plug or blast hole diamond bit of such construction that the likelihood of forming a core at the bit centeriseliminated.

A further object of the invention is to provide a plug or blast hole bit of such construction that plugging or clogging of the bit is avoided.

A still further object of the invention is to provide a plug or blast hole bit which is free of sharp corners or edges.

Another object of my invention is to provide a bit of the plug or blast hole type with which high rates of drilling speed can be maintained without bit vibration.

Another object of the invention is to provide a plug or blast hole bit of such construction that high bit speed may readily be maintained from top to bottom of the hole, as distinguished from prior plug bits wherein it is only possible to run the bit at high speed for a short distance, it being necessary thereafter materially to reduce the bit speed. In other words, my bit permits high bit speeds to a much deepe depth than is possible with conventional plug or blast hole bits.

In the accompanying drawings wherein I have illustrated an embodiment of my invention;

Fig. 1 is an end elevational view of the face of the bit;

Fig. 2 is a side elevational view; and

Fig. 3 is a diagrammatic view illustrating the shape of the end of the bit.

Referring to the drawings in detail, 2 designates the bit body and l the bit shank, the latter being threaded as is customary for attachment of the bit to the drilling equipment.

6 designates the diamonds of the bit. The bit may be of the cast type or of the powdered metal type. These two types of bit are well known to those skilled in this art so that no further explanation is needed so far as these features of the bit are concerned.

The working face of the bit is concaved at the center and convex from the edge of the concaved area to the bit periphery. The concaved area has been designated 8 and the annular convex area has been designated ID. As will be seen from the drawings, and particularly from the diagram of Fig. 3, the radii of the concave and convex areas 8 and I 0 are the same length.

2 Fig. 3 also illustrates that the concave and convex areas merge smoothly into each other and that the area 8 by reason of the fact that it is concave will provide a very much increased cutting area at the center point of the bit face than is possibleto obtain with conventional plug bits. This construction also eliminates th possibility of the formation of a core at the bit center.

The shank 4 of the bit is tubular as seen at 12. Drilled through the bit body from the face of the bit to the bore l2 of the shank is a hole M. This hole is offset appreciably with respect to the center of the bit face, extending from the edge of the concave area 8 rearwardly of the bit, diverging from the bit axis at a small angle (see Fig. 2).

The hole i l cooperates with a waterway l6 which extends from the outer end of the hole 14 obliquely across the face of the bit to the bit periphery and then lengthwise of the bit body as seen at 8, this portion it being slanted slightly with respect to It, so that the rear end of the waterway trails the outer or forward end.

The diamonds 2B which stud the walls of the concave area 3 are somewhat elongated in shape, and in positioning these diamonds in the bit they are so disposed that the long axis of each diamond extends radially of the bit face.

From all of the foregoing, it will be seen that my improved bit is of such construction due to the provision of the concave and convex areas 8 and EB and the offset bore M and cooperating waterway that the cuttings for a full out are washed away at each bit revolution so that plugging or clogging of the bit at the center and the formation of a core while drilling are avoided. It will be appreciated also that because of my novel construction large volumes of water may be used compared with conventional plug bits so that not only will the cuttings be washed away but I am assured of prope cooling of the bit despite the fact that the bit is operated at what the industry considers high speed.

What I claim is:

1. As an article of manufacture, a diamond plug bit, the working face of which is provided with a centrally disposed concave area surrounded by and merging with an annular convex area, said areas having the same radius of curvature, a hole for the passage of water through the bit, said hole extending from the working face of the bit at a point within said concave area offset with respect to the center of the bit face rearwardly to the bit shank, and a waterway on the working face of the bit extending obliquely from the forward or discharge end of 7 said hole to the bit periphery and from thence tudinal bore across the working face of the bit 7 to the bit periphery and from thence rearwardly along'the surface of the body of the bit.

3. As an article of manufacture, a diamond plug bit having a hollow shank, the Working face of said bit being provided with a centrally disposed concave area and an annular convex area, said areas having the same radius of curvature, and the two areas merging into each other, the

bit being bored longitudinally from a point in the concaved area offset with respect to the bit center to the bore of the hollow shank of the bit, and a waterway extending from the outer end of said longitudinal bore across the working face of the bit and rearwardly along the surface of the bit body.

4. As an article of manufacture, a diamond plug bit having a hollow shank, the working face of said bit being provided with a centrally disposed concave area which merges into a surrounding convex area, said areas having the same radius of curvature, the bit being bored from a point in the concaved area offset with respect to the bit center rearwardly in a direction diverging from the longitudinal axis of the bit to the bore of the hollow bit shank and a waterway extending obliquely from the outer end of said longitudinal bore across the working face of the bit and thence rearwardly along the surface of the body of the bit. l

5. As an article of manufacture, a diamond plug bit having a hollow shank, the working face of said bit being provided with a centrally disposed concave area which merges into an annular convex area surrounding the same, said areas having the same radius of'curvature, the

bit being bored from a point in the wall of the concaved area offset with respect to the bit center rearwardly in a direction diverging from the longitudinal axis of the bit to the bore of the hollow bit shank, and a waterway extending obliquely from the outer end of said longitudinal bore across the working face of the bit and thence rearwardly along the surface of the body of the bit in such a direction that the rear end of the waterway trails the forward end of the same.

EDGAR C. BONSALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 7 Number Name Date 2,217,889 Carpenter et al Oct. 15, 1940 2,264,617 Carpenter et al Dec. 2, 1941 Williams Jan. 3, 1950 

